Abstract Blood brain barrier (BBB) disruption is an integral feature of neurological diseases as diverse as multiple sclerosis, acute hemorrhagic leukoencephalitis (AHLE), traumatic brain injury, stroke, cerebral malaria, viral hemorrhagic fevers, epilepsy, glioblastoma, alzheimer's disease, and HIV dementia. A fundamental question in these diseases is the extent inflammatory immune cells contribute to CNS vascular permeability. This lack of understanding currently undermines therapeutic approaches to treat neurological disease in which uncontrolled BBB disruption contributes to pathology. My research program was the first to demonstrate that CD8 T cells have the capacity to disrupt BBB tight junctions using a novel murine model. Using this model, we have developed a tractable approach to dissect immune-mediated mechanisms of vascular endothelial growth factor (VEGF) mediated BBB disruption using a variation of Theiler's Murine Encephalomyelitis Virus (TMEV) and the Plasmodium berghei ANKA (PbA) model systems. Our central hypothesis is CD8 T cells promote neuronal expression of VEGF which results in disruption of cerebral endothelial cell tight junctions and vascular permeability. We will test our central hypothesis through the following aims: Specific Aim #1 ? Determine the extent direct engagement of antigen specific CD8 T cells with neurons promotes VEGF expression and ensuing vascular changes. Specific Aim #2 ? Determine the extent neuronal expression of VEGF and its receptors contribute to CD8 T cell-initiated BBB disruption. Specific Aim #3 ? Evaluate the contribution of neuronal VEGF to CD8 T cell-mediated BBB disruption in the Plasmodium berghei ANKA (PbA) model of experimental cerebral malaria. To our knowledge, no other laboratories have a similar mouse as PIFS that capitalizes on readily inducible acute CNS vascular permeability mediated by a well-defined immune cell type. Confirming the existence of homologous inflammatory mechanisms in humans would be the first step toward therapeutic intervention of neurological diseases in which neuroinflammation induced CNS vascular permeability plays a significant part. To accomplish these aims, we will employ: (a) flow cytometry, (b) behavioral studies, (c) high resolution confocal microscopy and immunohistochemistry, (d) 2-photon intravital microscopy (e) protein biochemistry, and (f) small mammal MRI.